Industrial doors are used in industrial or commercial buildings to separate zones of different temperature or humidity conditions or prevent noise propagation between the zones. One common form of industrial door is a roll door in which a fabric door panel is coiled on a drum located above the header of the doorway. As the door panel of a roll door is composed of fabric material, it provides an attractive appearance, and due to the flexible nature of the door panel, it is less susceptible to denting or other damage as compared to a rigid door.
The typical roll door is power operated and incorporates a drive mechanism that is connected to the drum and operation of the drive mechanism in one direction will uncoil the door panel to move the panel to a closed position, while operation of the drive mechanism in the opposite direction will act to wind the panel on the drum and move the door panel to the open position.
In addition, the drive mechanism also includes a clutch which can be manually operated to disconnect the drive. A clutch is required in order to provide manual operation of the door in case of fire or a power outage or during maintenance or installation of the door. The drive mechanism adds considerably to the overall cost of the roll door.
Industrial roll doors are commonly used with loading docks. In installations where there are multiple loading docks, the docks are relatively close together with perhaps only about 18 inches between adjacent docks. Because of the close proximity, a conventional power operated roll door cannot be utilized in these installations.
Therefore, there has been a need for an inexpensive, compact, manually-operated, industrial roll door.